An empirical correlation between print through values and magnetic characteristics of chromium dioxide powders

While the measurement of the magnetic pro perties of the powders could be accomplished routinely, using gram-amount of materials, the determination of the print through requires the preparation of a magnetic tape in standard conditions. This latter fact introduces severe constraints for what concerns the amount of the material used and the reproducibility of the preparation method also in that critical laboratory phase which is the development of new materials or the improvement of older ones. It has been therefore thoroughly investigated the possibility of correlating magnetic properties of the CrO
2
powders, such as the specific saturation magnetization (σ
s
), the coer civity factor (H
r
-H
c
)/H
c
percent and the magne tization at low fields with the print through. It has been shown that a good correlation is observed when those magnetic parameters are displayed in a function of the type:
P.T. = A [\sigma_{s}/C.F. \times M.R.] + B
and even better with a function of the type:
P.T. = A [(\sigma_{s})^{a}/(C.F.)^{b} \times (M.R.)^{c}] + B
where P.T. is the print through value of the magnetic tape, C.F. is the coercivity factor defined above, M.R. = magnetization at 40 Oe/ saturation magnetization and a, b and c are numerical constants which could be obtained with a computer optimization procedure.